Ah ha yeah I understand the question now, since I can not actually just give you the answer let me pose this question to you,

for 8 part a, you used the fact that both sets of variables such as [tex] s_{1} \;\; s_{2} \;\; e_{1} \;\; e_{2} \;\; v_{1} \;\; v_{2} [/tex] etc actually have the same relations to one another, but in reality the orbits are not circles and thus not uniform, what does that tell you?

for 8 part b, it is kind of hard for me to come up with a way of saying this without giving it away but here is a question, when finding the two equations that described the two problems did you use information from one equation to complete the other? If they were not circles would you still have been able to do the operation that you did? (what I said in the prior paragraph could be carried over here.)